Band structure engineering of van der Waals heterostructures using ferroelectric clamped sandwich structures

摘要

A novel strategy of band structure engineering of van der Waals heterostructure is proposed using a ferroelectric (FE) clamped sandwich structure from first principles. The validity of the strategy is demonstrated in the sandwich structure of In_2Se_3/bilayer-CrI_3/In_2Se_3 (In_2Se_3/bi-CrI_3/In_2Se_3) made by ferroelectric In-2Se_3 layers and semiconducting bilayer (SB) CrI_3. Four states with different band structures in the FE/SB/FE sandwich structure are obtained by switching the FE polarization in the top and bottom In_2Se_3 layers. Two of the states possess spin-splitting semiconducting band structures with opposite spin channel in conduction bands which are generated from a spin-degenerated band structure of the CrI_3 bilayer, resulting in an electric field controllable and nonvolatile four states spin-field effect transistor. The strategy of using FE layers to engineer band structures and generate spin-splitting semiconducting band structure in van der Waals heterostructure opens a new route in two-dimensional electronics and spintronics.